Water Treatment

Chlorine and its compounds are used to sterilise drinking water and water in swimming baths.
Kills cholera, typhus bacteria and E. coli.
Chlorine is toxic so can only be used in small amounts.
Some chlorine persists in water - prevents re-infection further down the supply.
Also inhibits the growth of algae, eliminating bad tastes and smells.
Usually chloric (I) acid or sodium chlorate (I) is added to water but calcium chlorate (I) may also be used as it is less hazardous.
Using chlorine compounds reduces the risks of using elemental chlorine.

Chlorine gas is very harmful - irritates the respiratory system.
Liquid chlorine on skin or eyes can cause severe burns.
Amount of chlorine added is monitored - due to toxicity and to prevent excess chlorine reacting with organic waste products in water to form organochlorine compounds that may be toxic / carcinogenic.

Failure to chlorinate water can cause serious health risks for potentially thousands of people.
Risks and benefits need to be weighed up when making decisions about whether to add chemicals to drinking water supplies.

	Created by Melissa Lamb over 7 years ago

AS - Level Chemistry (Group 7 - Halogens) Note on Uses of Halogens - Bromine & Chlorine, created by Melissa Lamb on 06/06/2017.